Fine needle aspiration biopsy (FNAB) is a cost-effective and rapid procedure that uses a syringe to sample fluid from a cyst or remove clusters of cells from a solid mass for diagnostic purposes. The effectiveness of FNAB is operator-dependent and the diagnostic yield can be low, especially for adipose-rich and masses where the percentage of non-diagnostics aspirates is relatively high (over 20%). Proper needle placement can substantially reduce the number of the non-diagnostic aspirates and improve the sensitivity and specificity of the procedure. Advanced techniques now exist to do the FNAB guidance, like stereotactic CT or ultrasound, but they are expensive, require additional personnel and they are not always available in small clinics. Physical Sciences Inc. (PSI) proposes to develop a simple and low-cost instrument based on Low Coherence Interferometry (LCI) that will be used as a guidance tool for needle placement during the FNAB procedures. In Phase I a benchtop system with a smart optical probe for FNAB guidance will be developed and a pilot in vitro clinical study on various tissue specimens will be conducted to demonstrate the capability of the system to differentiate tissue types (adipose, fibroglandular, and tumor). Also, an animal study will be performed to demonstrate the capability of the instrument to differentiate tissue-types in vivo. Phase II of the project will focus on the development of a portable, low cost clinical system with a disposable probe and a clinical study on patients will be performed at the Massachusetts General Hospital to prove the effectiveness of the instrument in the guidance of needle during the FNAB procedures. The implementation of this guidance modality would provide a relatively inexpensive and completely objective adjunct to the FNAB procedures. It will substantially increase the yield of the FNAB's, and will improve the overall procedure and cost efficiency of the biopsy test. Relevance of This Research to Public Health: The proposed research could substantially improve biopsy yield and therefore cancer screening, allowing for detection at an early stage when it is treatable and potentially curable. It is evident that earlier diagnosis results in an improved outcome and reduced mortality from disease. [unreadable] [unreadable]